3-mercapto-2-chloropropyl-n,n-dihydrocarbyl thiolcarbamates

ABSTRACT

By a method of synthesis based on a secondary amine, carbon disulfide and epichlorohydrin there are produced 2,3epithiopropyl N,N-dialkylthiolcarbamates which are used as selective herbicides, particularly in pre-emergent control of grasses such as brome and volunteer oats.

United States Patent 1 Doyle, Jr.

[111 3,728,371 51 Apr. 17, 1973 3-MERCAPTO-Z-CHLORQPROPYL-NN- DIHYDROCARBYL THIOLCARBAMATES [75] Inventor: William Carter Doyle, Jr., Leawood,

Kans.

[73] Assignee: Gulf Research & Development Company, Pittsburgh, Pa.

[22] Filed: Apr. 23, 1971 21] Appl. No.: 137,079

Related U.S. Application Data [62], Division of Ser. No. 854,344, July 30, 1969, Pat. No. 3,634,457, which is a division of Ser. No. 625,603, March 24, 1967, Pat. No. 3,510,290.

2,941,879 6/ 1960 Goodhue ..260/455 A 3,342,835 9/1967 Lies ..260/455 A FOREIGN PATENTS OR APPLICATIONS 886,425 l/ 1962 Great Britain.. ..260/455 A OTHER PUBLICATIONS Geigy, Carbamic Acid Ders. etc.," (1963), CA 59, p.

Tilles, Thiolcarbamates, Prep. and Molar Refractions 1958) JACS 81 pp. 714-727 1959) Primary Examiner-James 0. Thomas, Jr. Assistant Examiner-G. Hollrah v Attorney-Richard L. Kelly, Carl A. Cline, Forrest D.

Stine and Howard F. Van Denburgh ABSTRACT By a method of synthesis based on a secondary amine, carbon disulfide and epichlorohydrin there are produced 2,3-epithiopropyl N,N-dialkylthio1carbamates which are used as selective herbicides, particularly in pre-emergent control of grasses such as brome and volunteer oats.

10 Claims, No Drawings 3 -MERCAPTO-Z-CHLOROPROPYL-N ,N- DIIIYDROCARBYL TI-IIOLCARBAMATES SUMMARY OF INVENTION This application is a division of U. S. Ser. No. 854,344, filed July 30, 1969, now U. S. Pat. No. 3,634,457, which is a division of U. S. Ser. No. 625,603 filed Mar. 24, 1967, now U. S. Pat. No. 3,510,290.

DETAILED DESCRIPTION I. Synthesis Methods The compounds of the series, 2,3-epithiopropyl N,N- I I dialkylthiolcarbamates, are prepared by two general methods, one a three-step process, with isolation of intermediates and the other essentially a single-step It is known that reaction of carbon disulfide with a m secondary amine readily produces the amine salt of a corresponding dithiocarbamate as illustrated below:

The product possesses very selective herbicidal activity against a few grasses, particularly brome and oats, and is readily converted to the corresponding epithio ester which possesses similar herbicidal activity and greater chemical stability:

Y hydrocarbon substituents may include alkyl, cycloalkyl from cyclopropyl to cyclohexyl and lower alkenyl groups.

process. Method A R o R s on \NII 0s; ciornofi xnn N( JSCHz( /I1CH2Cl R R/ lac- R\ I RN 3 e SH- NCSCHaCH----CH1 N son, Hom- R R III 11 The initial low temperature reaction is believed to in-- clude reaction of epichlorohydrin with N,N-dialkyldithiocarbamic acid.

The reaction of epichlorohydrin with a salt (which may also be a metal salt, as well as an amine salt) appears to require a higher temperature than reaction withthe acid.

In an experiment in which both routes were used to prepare the same N,N-diethyl thiolcarbamate compound, the yields were roughly equivalent. In syntheses based on morpholine, dicyclohexylamine or isopropyl cyclohexylamine as starting materials, Method B has been found to be the only successful route, with the dithiocarbamate salt being the sole product obtained in the first step of Method A, rather than the more reactive free acid.

Intermediates I and II are isolable, though not easily purified. I is thermally unstable, rearranging to II in a matter of several hours to several days, depending on the nature of the N substituents. The structure of I is thought to be asshown, based on its infrared spectrum and the NMR spectrum of its phenylurethane derivative. Intermediate II is relatively stable and suitable for herbicidal use, various type II compounds showing qualitatively the same activity as. the corresponding type III compounds. The structureof II 'is notfirmly established but present evidence favors the structure shown in the reaction diagram below.

.r a" N NC s CHzCIIGlIzSII "l... o s omenom 11 n 11 111 clncooi CHsOOCI NC s omdnomscom On treatment with acetyl chloride both 11 and Ill give cmpounds.(lV) having the same NMR spectrum and,

while this spectrum is not readily interpreted, and a mixture of position isomers cannot be excluded, comparison with model compounds suggests the structure shown.

The success of this sequence of reactions leading to a thiolcarbamate apparently requires a secondary amine as starting material. In three instances in which a primary amine was used the crude products decomposed extensively and no epithiopropyl thiolcarbamate (111), was obtained. In one experiment, starting with ten.- butyl amine, tert.-butyl isothiocyanate was found among the products of decomposition.

The final products (111) of the sequence are distillable liquids or crystalline solids. Some care must be exercised to prevent excessive heating during distillation. Otherwise the following decomposition readily occurs:

Thisthermal decomposition, if desired, may be used as an efficient and probably the most economical method of preparing allyl thiolcarbamates, which are products of established utility. (See, for example, British Pat. No. 808,753.)

11. ILLUSTRATIVE PROCEDURES Method A To a well stirred mixture of 38.0 g. (0.5 mol) of carbon disulfide and46.3 g. (0.5 mol) of epichlorohydrin in an ice-salt bath is added 36.5 g. (0.5 mol) of anhydrous diethylamine during 1 2 hours at 0 to -5. The mixture is stirred an additional 30 minutes, then let warm slowly to room temperature. At this point the reaction mixture is essentially 3-chloro-2-hydroxypropyl N,N-diethyldithiocarbamate, (I; R,R=Et), a

viscous yellow oil with no detectable unreacted starting materials present.

Heatingof the reaction mixture for 2 hours at 80 90 under vacuum gives 1 g. of crude rearrangement product- 11 (R,R'=Et). The course of the rearrangement may be easily followed by the disappearance of infrared absorption-bands at 2.95 (OH) and 1015p. (C=S) with the appearance of bands at 3.92 1. (SH) and 6.0 (C=O). The rearrangement is also accompanied by a marked decrease in viscosity.

To 29 g. (0.12 mol of the crude rearranged product in 100 ml. of ether is added slowly 12 g. (0.12 mols) of triethylamine. Reaction is immediate, causing the ether to reflux gently and precipitating 10.8 g. of

. triethylamine hydrochloride. The solution is filtered, evaporated and vacuum distilled, giving 15.1 g. (61.4

percent yield overall) of 2,3-epithiopropyl N,N0diethylthiolcarbamate (Ill; R,R=Et), b 119 20?.

Method B A solution of 36 g. (0.173 mol) of diethylammonium diethyldithiocarbamate and 15.0 g. (0.162 mols) of epichlorohydrin in 100 ml. of dioxane is heated to reflux. Shortly after heating is begun, a crystalline precipitate appears. After two hours, the solution is cooled and filtered to recover 15.4 g. of diethylamine hydrochloride. The filtrate is vacuum distilled to remove the bulk of the solvent, leaving 33.2 g. of a viscous brown oil. Extraction of this'oil with ether, de-

cantation and evaporation of the ether gives 25.7 g. of residue, distillation of which gives 17.7 g. of III, R,R Et.

In Table l are listed the compounds of type 111 prepared by the above procedures.

TABLE I R O S N- SCH2CH---- OH;

R R Method Yield 8.1. or M,P. Ethyl Ethyl A 61.4 1 l9-20/0.2mm. Ethyl Ethyl B 53.3 1 19-20/1.2mm. Propyl Propyl A 46.5 l33-4/1.2mm. lsopropyl lsopro A 54.0 1 17-18/0.4mm.

py Hexyl Hexyl A 52.5 128-60'/0.8mm. CH C H OCH CH2 B 34.1 .74-5' Methyl Methyl B 9.0 107/O.3mm. Allyl Allyl A 35.0 128-3370. lmrn. 2-methoxy 2-methoxy- A 24.0 l40-55/0.3-0.4$mm. -ethyl ethyl Butyl Butyl A 60.5 l43-53/0.5-0.9mm.

lsobutyl lsobutyl A 24.0 l40-3/0.5mm. Benzyl Methyl A 73.0 Crude material, not

distillable n 1.5974 Benzyl lsopro A 77.5 Crude material, not

distillable n 1.5773 py lsoamyl lsoamyl A 23.0 157-66/0.1-0.9mm. Butyl Methyl A 49.5 137-40/0.9mm. Benzyl Benzyl A 72.5 Crude material, not

distillable n 1.6142 Furfuryl Methyl A 86.0 Crude material, not

distillable n 1.5763 tetrahydro Methyl A 53.5 Crude material, not

distillable a 1.5581 -furfuryl Octyl Methyl A 88.5 Crude material, not

distillable n 1.5156 Cyclo Methyl A 86.0 7 MP. 55.5 58" hexyl Butyl Ethyl A 9.5 122 670.1 mm. Propyl Methyl A 46.0 129 34'/0.8 mm. lsopro Ethyl A 56.5 129 31/,0.8 mm. py Cyclo lsopro B 90.0 Crude material, not

diltillable n 1.5500 hexyl pyl Cyclo Cyclo 88.0 M.P. 96.6 98" hexyl hexyl Cyclo Ethyl 82.0 Crude material, not

diltillable 11,," 1.5503 hexyl Yield based on epichlorohydrin charged. Crude product crystallized and was recrystallized from hexane.

. i m. HERBICIDAL USE Pre-emergent herbicidal activity was evaluated by means of the following procedure:

A solution was prepared by dissolving 290 mg. of the compound to be tested in 200 ml. of acetone. Disposable paper half-flats were prepared and seeded, then sprayed with the acetone solution at the rate of 20 pounds of active chemical per acre of sprayed area. One flat, which had been seeded with alfalfa, brome,

flax, oats, radishes and sugar beets was held at'75'F. day temperature; another seeded with corn, coxcomb,

Type of Action Degree C chlorosis (bleaching) 0 no effect N necrosis l slight effect 2 moderate effect 3 severe efiect G growth inhibition F formative effect (abnormal form of growth) K non-emergence 4 maximum effect (all plants died) Following are tabulated the results of tests according to the above procedures on a representative group of 15 I claim: 1. The composition represented by the structural formula in which R and R are allyl or saturated hydrocarbon substituents containing a total of less than twelve carbon atoms.

2. The composition according to claim 1 in which R and R are allyl substituents.

3. The composition according to claim 1 in which R and R are butylsubstituents. V 4. The composition according to claim I in which R thiolcarbamates. and R are isobutyl substituents.

lRE-EMERHEN! 111 1111110111111. Amlvi'lw" Compound It s NC-S-CH1OH. M0111 R Crab- Cox- Mil- Soyot- Al- Rad- Sugar R R grass comb Bronte let hcan ton lalt'a Oats Corn Flax ish beet G1 (11 Ethyl F1 (1 F1 (1 (11 0 (11 (1 0 0 (1 =1 150mm" ISOPYODYI --1 (1 G1 K4 (12 (11 0 (1 (11 (1 0 (1 0 Pro 1 Pm l 5 G3 (1:1 12 Dy DY 1 F3 (11 K4 F3 (11 (11 (1 K4 (1 (1 (11 (11 Hexyl 4 I8Xy1 1 I (IS 0 U U (l l) U (I l] (1 0 0 2 (12 (11 Butyl Ethyl -1 F2 (1 K4 F2 (1 (Fl K4 (1 (1 0 G1 11 lsopropyl Ethyl (1 0 4 (1 (1 F1 (12 (1 (1 0 (1 (1 2 (1 (1 oyclohexyL-m Isopmpyl F1 (1 G2 l l (1 0 F1 G2 0 0 0 0 G1 (11 (12 o1 Ethyl F1 (1 K4 F1 (1 (1 F2 os (11 F1 (1 G1 K2 (31 Methyl i (1 (1 ('12 o (1 (1 F1 (11 (1 o 0 0 I K; E 0

1 K3 Imbutyl lwbuty (1:1 (11 K4 (1:1 (11 (1 (11 K4 (1 (1 (1 (1:1 Isopcntyl lsopcntyl (l (1 (1 U (1 (I (1 (1 1f- 0 f) 0 MI] Mn 5 1. F1 1 K3 Y y --1 (11 (1:1 (1:1 (11 (12 (11 (1 (12 (1 (1 (1 G3 K2 H (11 ('ydohcxyl-m- (1 :1 (12 (1 (1 (1 F1 (11 (1 (1 (1 0 lsopropyLv .H. lsopropyl... 0 U K4 (1 ll (1 (1 (l3 (1 (I U 0 (1:1 n (2 (1:1 WOW] -"i F2 (11 K4 1 (11 (11 (1 F3 n (11 (1 Ethyl isopropyl 1 11 K4 (1 (1 t) (1 G2 (I I] C 0 F (1:1 (12 (11 (13 mm] F2 (1 K4 2 (1 (1 F1 I12:1 (1 (1 (1 (11 K3 (11 :1 --1 (1s (12 (1:1 (12 (12 (11 F1 (1:1 (1 (12 ('12 (12 K3 (11 Imbutyl (11 (11 (1:1 K4 c1 (11 (12 (1 (1 0 G2 K2 K3 K2 Bum Bum (12 (13 (32 K4 (1 (1 (12 (11 (1 (1 0 g A1111 A1111 "("71 '21-; (11 m (11 "(ii 1 "('1 "('1 "a "a" G The tabulated data indicate clearly the pronounced selectivity of the pre-emergent herbicidal action of the compositions. Also demonstrated in the data is an absence of activity toward the test species when the N- substituents contain a total of twelve carbon atoms. Although lacking in the desired type of herbicidal activity, the higher N,N-dialkylthiolcarbamates are useful for other purposes, particularly in corrosion inhibiting formulations, alone or in combination with nitrogen bases of the polyamine type, and as fungicides. The compounds derived from the higher molecular weight secondary amines in general exhibit microbiological activity without substantial effect on plant life.

0 is butyl and R is ethyl.

9. The composition according to claim 1 in which R is cyclohexyl and R is ethyl.

10. The composition according to claim 1 in which R 65 is ethyl and R is isopropyl. 

2. The composition according to claim 1 in which R and R'' are allyl substituents.
 3. The composition according to claim 1 in which R and R'' are butyl substituents.
 4. The composition according to claim 1 in which R and R'' are isobutyl substituents.
 5. The composition according to claim 1 in which R and R'' are propyl substituents.
 6. The composition according to claim 1 in which R and R'' are isopropyl substituents.
 7. The composition according to claim 1 in which R is cyclohexyl and R'' is methyl.
 8. The composition according to claim 1 in which R is butyl and R'' is ethyl.
 9. The composition according to claim 1 in which R is cyclohexyl and R'' is ethyl.
 10. The composition according to claim 1 in which R is ethyl and R'' is isopropyl. 